Liquid changing device and gene sequencer

The invention provides a liquid changing device which is mounted on a soaking-type gene sequencer. The device sequentially comprises a reagent bottle, a rotary plunger pump, a first electromagnetic valve, a reagent tank, a second electromagnetic valve, a diaphragm pump, a collecting pipe and a waste liquid bottle which are communicated and connected through a pipeline; a liquid inlet and a liquidoutlet of the reagent tank connected to the pipeline are formed in the top of the reagent tank, the rotary plunger pump and the first electromagnetic valve are used for transferring and injecting a reagent into the reagent tank, and the reagent is controlled by a liquid level sensor arranged in the reagent tank to reach a preset liquid level; and the diaphragm pump and the second electromagnetic valve are used for sucking out a waste liquid from the liquid outlet and discharging the waste liquid into the waste liquid bottle. The liquid changing device has a stable liquid level, liquid changingand leakage with the outs